Oh, but he isn't wrong. It's quite likely that your 8000 inhabitants (which are a lot more than 100 families) live close enough together, just because of lack of giant lawns, so that your typical store owner is getting more than 100 customers.

So yes, it's not that you can't have single families, and it's not really about people having cars or not, it's the density, and therefore, it's the lawns and the streets that are too wide, making the number of places that you can go to in a 15 minute walk far smaller